Apparatus for drying and processing raw food material

ABSTRACT

A combined spray and rotary drying apparatus includes a spray dryer having a housing defining a spray drying chamber, an annular inlet and an outlet. A burner and atomizer sprayer are provided in the spray drying chamber. The outlet of the spray drying chamber feeds into a rotary drying drum. A raw material feed chute is also provided for feeding raw material of relatively low moisture content directly to the rotary dryer. Methods of drying a raw material and of processing raw animal parts are also disclosed.

This application is a divisional of U.S. patent application Ser. No.08/841,230, filed Apr. 29, 1997, entitled "Method and Apparatus forDrying and Processing Raw Food Material".

TECHNICAL FIELD

The present invention relates generally to the nutritional supplementprocessing field and, more particularly, to a method of processing rawanimal parts, a method of drying raw food material while preserving itsnutritional content and an apparatus for spray drying that raw foodmaterial.

BACKGROUND OF THE INVENTION

Food additives are substances that may be added to foods duringprocessing in order to improve desirable chemical or physicalcharacteristics and food quality. One of the most important forms offood additives are nutritional supplements. These typically compriseminerals and vitamins that are added to foods in order to restorenutritional values lost during food processing or to supplement thenatural content of the food nutrients. The importance of the use ofnutritional supplements to enhance the health and growth of farm animalshas long been recognized in the field of animal husbandry.

It has also long been recognized that the production of nutritionalsupplements from various by-products of food rendering operations ishighly desirable. Specifically, by establishing a commercial use forthese by-products, the economic viability of the food rendering processis enhanced and otherwise difficult waste material handling is reducedor altogether avoided. This is a particularly important aspect for thepoultry rendering industry where significant amounts of waste materialsare produced. Accordingly, various methods have been developed for theutilization and processing of feathers and offal as a nutritionalsupplement for food products. Such processes are generally disclosed in,for example, U.S. Pat. No. 3,272,632 to Speer and U.S. Pat. No.4,269,865 to Retrum.

One of the primary drawbacks in the prior art processing of wasteproducts such as feathers and offal into nutritional supplements hasbeen the heat degradation of various amino acids and proteins thateffectively eliminates these materials as a source of nutrition.Accordingly, a need is identified for an improved method of processingwaste products such as feathers and offal so as to avoid heatdegradation of important amino acids and proteins and thereby provide asupplement with enhanced nutritional values.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean economical and efficient method of processing raw animal parts into asupplement providing significantly enhanced nutritional values. Such asupplement may advantageously be utilized to promote the production ofblood plasma in young animals and more particularly, farm animals suchas piglets.

Yet another object of the present invention is to provide a method ofdrying raw food materials such as feathers and offal whereby the heatsensitive nutritional elements in those raw materials including aminoacids and proteins are maintained in an undegraded and digestible stateduring and following drying to a desired moisture content.

Yet another object of the present invention is to provide an apparatusfor more efficiently drying raw food materials.

Additional objects, advantages and other novel features of the inventionwill be set forth in part in the description that follows and in partwill become apparent to those skilled in the art upon examination of thefollowing or may be learned with the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outin the appended claims.

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention as described herein, an apparatus isprovided for drying raw material such as waste products includingfeathers and offal being processed as a food supplement. The apparatusincludes a spray dryer having a housing defining a spray drying chamberand an outlet. A burner is received in the spray dryer. Additionally,means are provided for atomizing and spraying the raw material into theapparatus. Further, a rotary drying drum is provided downstream from thespray dryer and includes an inlet in fluid communication with the outletof the spray dryer. Accordingly, the raw material being dried issequentially subjected to both spray drying and rotary drying in orderto bring that material to a desired moisture content.

More specifically describing the invention, the housing includes an endcap opposite the outlet and spaced inner and outer walls defining an airfeed passageway therebetween. The air feed passageway extends along theinner wall from adjacent the outlet to an annular delivery port adjacentthe endcap. This provides for preheating of the air and cooling to theinner shell prior to delivery into the spray drying chamber.

Preferably, the burner received in the spray dryer is a ring burner andthe atomizing spraying means includes a charging pipe and spray nozzleconcentrically disposed so as to extend through the ring burner into thespray drying chamber. Further, a conical deflector is provided in thespray drying chamber. The deflector concentrically projects around thecharging pipe and spray nozzle. This conical deflector deflects air fromthe annular delivery port outwardly toward the ring burner to provideeven heating temperature and more consistent spray drying through theelimination of hot and cold spots.

Additionally, the apparatus includes a pressurized air source and a rawmaterial feed source for delivering, respectively, air under pressureand raw material to the charging pipe and spray nozzle. The chargingpipe includes a raw material feed tube received within an air jacket forthe passage of the air under pressure. The air jacket effectivelyinsulates the charging tube from direct heating by the ring burner andthereby insures that the raw material is not dried therein so as to clogthe feed tube.

In accordance with another aspect of the present invention, a rawmaterial feed chute is provided downstream from the charging pipe andthe spray nozzle. This feed chute is utilized for delivering relativelylower moisture content raw material to the apparatus. Together, thespray dryer structure including the charging pipe for relatively highmoisture content raw material and the feed chute for relatively lowmoisture content raw material function to insure that the raw materialis evenly dried to a desired moisture content while simultaneouslypreserving the heat sensitive nutritional elements of the raw material(e.g. amino acids and proteins) from heat degradation which wouldotherwise reduce their nutritional value.

Still further describing the invention, a means is provided for drivingthe rotary drying drum. Further, the rotary drying drum includes adischarge outlet. Additionally, the apparatus further includes acollector in fluid communication with the discharge outlet of the rotarydrying drum. This collector functions to collect the dried raw materialof desired moisture content for purposes of further processing.

In accordance with another aspect of the present invention, a method isprovided for drying raw material and, particularly, waste material suchas hydrolyzed feathers and poultry offal being processed as a meal forfood supplement. The method includes both the spray and rotary drying ofthe raw material having a first, relatively high moisture content.Further, the method includes the subjecting of raw material having asecond relatively low moisture content directly to rotary drying withthe raw material having the first, relatively high moisture content.Thus, the lower moisture content material is not subjected to spraydrying. Accordingly, this lower moisture material is not subjected tohigher heat levels that might otherwise lead to degradation of importantheat sensitive amino acids and proteins. So as to insure that the rawmaterial is processed and dried efficiently, the raw material is sprayedwith pressurized air supplied at 60-85 and more preferably 75-80 psig.Further, an air stream velocity is maintained in the rotary drying drumof substantially 450-550 feet per minute.

Finally, in accordance with yet another aspect of the present invention,a method of processing raw animal parts is provided. That methodincludes the grinding of the raw animal parts to a size less than 0.25inches. This is followed by the heating of the raw animal parts toprovide a partial breakdown and the centrifuging of the raw animal partsto separate the partially processed raw animal parts into a meal, awater phase and an oil phase. Next is the subjecting of the water phaseto spray drying and also subjecting the meal and spray dried water phaseto rotary drying in order to recover any additional portion of meal inthe water phase and to drive off the water by evaporation. Thiseffectively eliminates any need to provide for separate waste waterprocessing and, of course, is an environmentally friendly approach.Finally, the method includes the collecting of the meal at a desiredmoisture content for further processing.

Still other objects of the present invention will become apparent tothose skilled in this art from the following description wherein thereis shown and described a preferred embodiment of this invention, simplyby way of illustration of one of the modes best suited to carry out theinvention. As it will be realized, the invention is capable of otherdifferent embodiments and its several details are capable ofmodification in various, obvious aspects all without departing from theinvention. Accordingly, the drawings and descriptions will be regardedas illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawing incorporated in and forming a part of thespecification, illustrates several aspects of the present invention andtogether with the description serves to explain the principles of theinvention. In the drawing:

FIG. 1 is a partially sectional, partially schematic view of theapparatus of the present invention for the combined spray and rotarydrying of raw material;

FIG. 2 is a detailed cross-sectional view of the spray dryer section ofthe drying apparatus shown in FIG. 1;

FIG. 2a is a detailed cross sectional view along line 2a--2a of FIG. 2showing the spray dryer section;

FIG. 3 is a cross-sectional view of the rotary drying drum section ofthe apparatus shown in FIG. 1.

FIG. 4 is a cross-sectional view of the primary solids or meal collectorsection of the drying apparatus of FIG. 1;

FIG. 5 is a detailed view showing the seal detail between the spraydryer section and the rotary drying drum section;

FIG. 6 is a detailed cross-sectional view showing the seal detailedbetween the rotary drying drum section and the meal collector section;and

FIG. 7 is a schematical block diagram showing the method of the presentinvention for processing raw animal parts.

Reference will now be made in detail to the present preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawing.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to FIGS. 1-6 showing the apparatus 10 of thepresent invention for drying raw material such as a nutrient supplementformed from hydrolyzed feathers, whole blood and poultry offal. Asgenerally shown in FIG. 1, the apparatus 10 includes a spray dryersection 12, a rotary drying section 14 and a primary solid/mealcollector section 16.

More specifically, the spray dryer section 12 includes a housingincluding an outer cylindrical wall 18 and an inner cylindrical wall 20.As shown, the inner cylindrical wall 20 is concentrically disposed andextends into the outer cylindrical wall 18 so that an annular air feedpassageway 22 is defined therebetween. This air feed passageway 22extends along the inner wall 20 to an annular delivery port 24 adjacentan endcap 26 that closes one end of the outer wall 18. Together, theouter wall 18, inner wall 20 and endcap 26 define a spray drying chamber28 into which the air is fed through the annular delivery port 24.

As further shown in FIG. 1 and with reference in detail to FIGS. 2 and2a, a ring burner 30 is received in the spray drying chamber 28 so as tobe concentrically disposed relative to the inner wall 20. Additionally,a raw material atomizing sprayer, generally designated by referencenumeral 32 is mounted for relative sliding movement in the endcap 26.The atomizing sprayer 32 includes a charging pipe 34 having pressurizedair and raw material feed inlets 36, 38 at its proximal end and a spraynozzle 40 at its distal end. As shown, the charging pipe 34 isconcentrically disposed so as to extend within the ring burner 30 intothe spray drying chamber 28. As further shown with reference also toFIG. 7, the pressurized air inlet 36 is connected to a pressurized airsource 42 which provides or supplies air at substantially 60-85 and morepreferably 75-80 psig. Similarly, the raw material inlet 38 is connectedto a raw material feed source such as a storage tank 44 containing theraw material to be processed. Specifically, raw material from thestorage tank 44 is received at the inlet 38 and passes through a feedtube 46 to the nozzle 40. The pressurized air from the pressurized airsource 42 is received at the pressurized air inlet 36 and travelsthrough the charging pipe 34 which functions as an air jacket around thefeed tube 46 (see also FIG. 2a) thereby protecting the raw material inthe feed tube from the high temperatures in the dryer produced by thering burner 30. Accordingly, no drying of the raw material occurs in thefeed tube 46 and free flow of the raw material through that tube isassured. Further, the air in the charging pipe/jacket 34 is preheated sothat no moisture is added to the raw material being dried.

Since the atomizing sprayer 32 may be moved/slid into and out of the endcap 26, it should be appreciated that the distance the nozzle 40projects into the spray drying chamber 28 may be adjusted. Thus, morerapid drying may be provided by positioning the nozzle at, for example,point A (see FIG. 2). In this position the raw material is sprayed fromthe nozzle 40 adjacent to the ring burner 30 where it is subjected tohigher drying temperatures. Alternatively, the nozzle 40 may bepositioned at, for example point B (again see FIG. 2). In this positionthe raw material is sprayed from the nozzle 40 further downstream fromthe ring burner 30. Thus, there is a less direct application of heat andthe raw material is subjected to lower drying temperatures. The positionof the nozzle 40 relative to the burner ring 30 may be adjusted to meetthe needs of the particular application.

As also shown in FIGS. 1 and 2, a conical deflector 48 is carried by andconcentrically projects around the charging pipe 34. This conicaldeflector 48 serves to deflect air from the annular delivery port 24outwardly toward the ring burner 30. This advantageously insures evenheating of the air thereby enhancing dryer performance by substantiallyeliminating any hot spots or cold spots which might otherwise lead toinconsistent drying of product.

As further shown in FIGS. 1 and 2, the inner wall 20 of the spray dryersection 12 defines an outlet 50. This outlet 50 directly communicateswith the drying chamber 52 defined by the rotary drum 54 of the rotarydrying section 14. Additionally, a raw material feed chute 56 isprovided in the inner wall 20 of the spray dryer section 12 downstreamfrom the charging pipe 34 and spray nozzle 40. It should be appreciatedthat relatively lower moisture content raw material is delivered throughthis feed chute 56 so that it is not as directly subjected to the heatfrom the ring burner 30. This functions to protect the temperaturesensitive elements including amino acids and proteins of the rawmaterial in this lower moisture content material from heat degradationthat would otherwise adversely affect the nutritional value of thesubsequent meal product.

The seal between the spray dryer section 12 and the rotary dryer section14 is best shown in FIG. 5. Specifically, the stationary inner wall 20of the housing of the spray dryer section 12 includes an outwardlyprojecting, substantially u-shaped sealing flange 58. The rotary drum 54of the rotary drying section 14 includes an inwardly extending,substantially n-shaped flange 60 that freely meshes with the cooperatingsubstantially u-shaped flange 58 carried on inner wall 20. Together, thesubstantially u-shaped flange 58 and substantially n-shaped flange 60provide a baffle-like seal which minimizes air flow losses as the airtravels from the spray dryer section 12 to the rotary drying section 14.

The rotary drying section 14 is of a design generally well known in theart. Specifically, the rotary drum 54 including a heat insulating shroud55 incorporates at least two tire assemblies 62. Each tire assembly 62includes a tire 64 mounted by means of shims 68 on a band 66 secured tothe drum 54. Each tire assembly 62 rides in a track assembly generallydesignated by reference number 70. Each track assembly 70 extends alongan arc of substantially 120-180° and includes a series of alignedtrunnion rollers 72 that receive a tire 64 and serve to support theweight of the rotary drum 54. Thrust rollers 73 maintain the tires 64 inalignment with the trunnion rollers 72. A motor 74 is provided to drivethe rotary drum 54 through means of a chain 75 that engages a sprocket76 mounted to the drum.

As further shown in FIG. 3, the rotary drying drum 54 includes a seriesof targets or plates 78 supported by mounting brackets 79 so as to bedisposed concentrically within the center of the drum 54. These functionto divert the air flowing through the rotary drum 54 and, therefore, theraw material being dried and conveyed by that air toward the sidewall ofthe dryer drum. This functions to enhance the drying action in a mannerknown in the art.

The outlet 82 of the drying drum is connected in fluid communicationwith the inlet 83 to the housing 84 defining the primary solid/mealcollector 16. The seal formed between the rotary drum 54 and thecollector housing 84 is best shown in detail in FIG. 6. As shown, therotary drum 54 includes an outwardly projecting flange 86 and thecollector housing 84 includes an outwardly projecting substantiallyT-shaped flange 88. Boiler rope packing 90 is provided on the leg 92 ofthe T-shaped flange 88 as shown in FIG. 6. This arrangement guardsagainst contamination with cooler atmospheric air and insures bestpossible dryer efficiency.

The primary solids/meal collector 16 also includes a pair of dischargescrews 94, 96. The first discharge screw 94 is longitudinally alignedwith the rotary drum 54 of the rotary drying section 14. This dischargescrew 94 is driven by a motor 98 and feeds dry raw material to thesecond, partially underlying discharge screw 96. The second dischargescrew 96 is driven by a motor (not shown) and delivers the dried rawmaterial to a discharge chute (not shown) for further processing. Anupper discharge duct 99 directs the air stream from the solids/mealcollector 16 to a cyclone 114 in accordance with a further descriptionof the processing method set forth below (see also FIG. 7).

The use of the drying apparatus 10 of the present invention will now bedescribed in detail in conjunction with a method of drying raw materialand a method of processing raw animal parts.

In accordance with the methods and as illustrated in FIG. 7, rawmaterial of poultry offal is fed from a bin 100 and delivered to agrinder 102 where it is ground to the desired size and consistency (e.g.no pieces greater than 1/4 inches in diameter). Following grinding, theraw material is fed from the grinder 102 to a heating unit 104. Therethe product is heated to between 195-205° F. in order to partially breakdown the raw material into meal, a water phase and an oil phase. Thesethree phases are then delivered to a three way centrifuge 106 where theoil is separated and delivered to oil storage vessel 108.Simultaneously, the water phase is delivered to a spray water storagetank 44.

From there, the water phase is delivered by means of pump 110 to the rawmaterial inlet 38 of charging pipe 34. Compressed air from the source 42is delivered to the pressurized air inlet 36 of the same charging pipe34 and the air and raw material are sprayed together through the nozzle40 in a full cone spray pattern into the spray drying chamber 28 of thespray dryer section 12. The burner ring 30 incorporates inwardlydirected gas jets that direct the flames toward the nozzle 40. As aresult of the spray pattern and inwardly directed jets, the raw materialis quickly dried so as to avoid any sticking to the walls of theapparatus during the drying process. Simultaneously, meal from the threeway centrifuge 106 is delivered to the feed chute 56 for delivery intothe rotary dryer 14 of the drying apparatus 10 as also described ingreater detail above.

As a result of this arrangement, it should be appreciated that the waterphase is subjected to spray drying in the spray dryer section 12 andthen rotary drying in the rotary drying section 14 while the meal isonly subjected to rotary drying in the rotary drying section. Hence, thehigher moisture content water phase is subjected to higher temperaturesand greater drying to drive off the water through evaporation andrecover additional raw material for meal. Simultaneously, the relativelylow moisture content meal is subjected to lower temperatures and lessdrying. Accordingly, any heat sensitive amino acids, proteins and othersources of nutrition contained therein are protected from heatdegradation. Processed meal is then recovered in the primary solids/mealcollector section 16.

In order to insure proper operation of the drying apparatus, thepressurized air from the compressed air source 42 is supplied atsubstantially 60-85 psig and more preferably 75-80 psig. Simultaneously,an induced draft fan 112 is provided downstream to insure that an airstream velocity of substantially 450-550 feet per minute is maintainedthrough the spray dryer section 12 and the rotary drying drum 54 (noteAction Arrows A in FIG. 1). It is this air stream that entrains thespray dried raw material and conveys the same from the spray dryersection 12 to the rotary drying drum 54 where the spray dried rawmaterial mixes with the meal during rotary drying. This air stream alsocarries the mixed and dried raw material through the rotary drying drum54 to the primary solids collector 16. A cyclone 114 and scrubber 116clean the air before it is exhausted into the environment. Mealrecovered in the primary solids collector 16 and cyclone 114 is thendelivered to a mill 118. From the mill 118, the meal is subjected tosizing by means of a screen 120 and then delivered to a storage bin 122to await further processing or shipment. Following processing the mealhas a moisture content preferably of between 5-8%.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Obvious modifications or variations are possible in light ofthe above teachings. The embodiment was chosen and described to providethe best illustration of the principles of the invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

What is claimed is:
 1. An apparatus for drying raw material saidapparatus comprising:a spray dryer including a housing defining a spraydrying chamber and an outlet; a burner received in said spray dryer;means for atomizing and spraying said raw material into said apparatus;and a rotary drying drum downstream from said spray dryer and includingan inlet in fluid communication with said outlet of said spray dryer. 2.The apparatus as set forth in claim 1, wherein said housing includes anendcap opposite said outlet and spaced inner and outer walls defining anair feed passageway therebetween.
 3. The apparatus as set forth in claim2, wherein said air feed passageway extends along said inner wall fromadjacent said outlet to an annular delivery port adjacent said end capproviding for cooling of said spray dryer housing and preheating of saidair prior to delivery into said spray drying chamber.
 4. The apparatusas set forth in claim 3, wherein said burner is a ring burner and saidatomizing and spraying means includes a charging pipe and spray nozzleconcentrically disposed so as to extend through said ring burner intosaid spray drying chamber.
 5. The apparatus as set forth in claim 4,further including a conical deflector concentrically projecting aroundsaid charging pipe and spray nozzle for deflecting air from said annulardelivery port outwardly toward said ring burner to provide even heating.6. The apparatus as set forth in claim 5, further including apressurized air source and a raw material feed source for delivering,respectively, air under pressure and raw material to said charging pipeand spray nozzle.
 7. The apparatus as set forth in claim 6, wherein saidcharging pipe includes a raw material feed tube received within an airjacket for the passage of said air under pressure to said spray nozzle.8. The apparatus as set forth in claim 1, wherein said burner is a ringburner and said atomizing and spraying means includes a charging pipeand spray nozzle concentrically disposed so as to extend through saidring burner into said spray drying chamber.
 9. The apparatus as setforth in claim 1, further including a raw material feed chute downstreamfrom said charging pipe and spray nozzle for delivering relatively lowermoisture content raw material to said apparatus.
 10. The apparatus asset forth in claim 9, wherein said feed chute is carried by said innerwall of said housing and extends into said rotary drying drum.
 11. Theapparatus as set forth in claim 1, further including means for drivingsaid rotary drying drum.
 12. The apparatus as set forth in claim 11,wherein said rotary drying drum includes a discharge outlet and saidapparatus further includes a collector in fluid communication with saiddischarge outlet of said rotary drying drum.
 13. An apparatus for dryingraw material to a desired moisture content, said apparatus comprising:aspray dryer including a burner, a sprayer and an outlet; and a rotarydrying drum including an inlet provided in direct fluid communicationwith said outlet of said spray dryer.
 14. The apparatus as set forth inclaim 13, further including a raw material feed chute extending intosaid rotary drying drum downstream from said burner.
 15. The apparatusas set forth in claim 14, further including a motor for driving saidrotary drying drum.
 16. The apparatus as set forth in claim 15, whereinsaid rotary drying drum includes a discharge outlet and said apparatusfurther includes a collector in fluid communication with said dischargeoutlet of said rotary drying drum.
 17. An apparatus for drying rawmaterial to a desired moisture content, said apparatus comprising:aspray dryer including a burner, a sprayer and an outlet; a rotary dryingdrum including an inlet for receiving raw material from said outlet ofsaid spray dryer; and a feed chute for delivering relatively lowmoisture-content raw material directly into said rotary drying drum.